The brain ammonium production is detoxified by astrocytes, the gut ammonium production is detoxified by hepatic cells, and the renal ammonium production plays a major role in renal acid excretion. As a result of ammonium handling in these organs, the ammonium and pH values are strictly regulated in plasma. Up until recently, it was accepted that mammalian cell transmembrane ammonium transport w...

Ammonium (NH(4)(+)) is a ubiquitous intermediate of nitrogen metabolism but is notorious for its toxic effects on most organisms. Extensive studies of the underlying mechanisms of NH(4)(+) toxicity have been reported in plants, but it is poorly understood how plants acclimate to high levels of NH(4)(+). Here, we identified an Arabidopsis (Arabidopsis thaliana) mutant, ammonium overly sensitive1...

A biocompatible fluoride receptor has been developed where the interaction between the boronic acid ester and amine (NH) results in fluoride ion selectivity and enhanced fluorescence quenching.

The role of the NH(3) ligands in the highly successful antitumour agents cisplatin and carboplatin is not fully understood. Suggestions that the ammonia ligands are involved in target recognition through hydrogen bond formation, e.g. with guanine-O6, have been questioned. Here, we review the roles and functions of NH(3) ligands of cis-PtCl(2)(NH(3))(2) and likewise of its trans-isomer in comple...

Activation of the adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1[ from turkey erythrocytes by isoproterenol decreased precipitously below 26 degrees. Certain unsaturated fatty acids enhanced the activation by isoproterenol up to 25-fold at reduced temperatures. The fatty acid also enhanced the formation of a persistent active state of the enzyme which was produced by preincu...

Both salicylic acid and ferricyanide induce flowering in the long-day plant Lemna gibba L., strain G3 under 8- and 9-hour short days. In both cases the effect is daylength-dependent. Salicylic acid is ineffective on daylengths less than 8 hours and ferricyanide is ineffective on daylengths less than 5 hours. When both substances are given together a striking synergistic interaction is observed,...

The effect of surface chemistry (nature and amount of oxygen groups) in the removal of ammonia was studied using a modified resin-based activated carbon. NH(3) breakthrough column experiments show that the modification of the original activated carbon with nitric acid, that is, the incorporation of oxygen surface groups, highly improves the adsorption behavior at room temperature. Apparently, t...

Two simple methods for dissolving salts of acid glycosaminoglycans with inorganic cations (e.g. Li+ and Na+) in dry dimethyl sulphoxide are described. Complete n.m.r. spectra of, e.g., Na+ and Li+ salts of chondroitin sulphate and keratan sulphate were obtained on these solutions. In [2H6]dimethyl sulphoxide the NH resonance of 2-acetamido-2-deoxy hexosides is in the range 7.2-8.0 delta, but is...

Two asymmetric polyoxomolybdates Na(6){Mo(2)O(5)[(Mo(2)O(6))NH(3)CH(2)CH(2)CH(2)C(O)(PO(3))(2)](2)}·16H(2)O (1) and (NH(4))(7)Na{MoO(2)[(Mo(2)O(6))NH(3)CH(2)CH(2)CH(2)C(O)(PO(3))(2)]}(4)·H(2)O (2) have been synthesized by the reactions of alendronic acid with molybdate. Structure analysis revealed that the polyoxoanions 1 and 2 can be described as dimeric and tetrameric aggregates of the {MoO(3...

RF pulse schemes for the simultaneous acquisition of heteronuclear multi-dimensional chemical shift correlation spectra, such as {HA(CA)NH & HA(CACO)NH}, {HA(CA)NH & H(N)CAHA} and {H(N)CAHA & H(CC)NH}, that are commonly employed in the study of moderately-sized protein molecules, have been implemented using dual sequential (1)H acquisitions in the direct dimension. Such an approach is not only ...